Variability of Chalcone Synthase in Chamomile Accessions (Matricaria chamomilla).

Chamomile (Matricaria chamomilla) is an important medicinal plant whose beneficial activities partly rely on certain flavonoids. The first dedicated step in flavonoid biosynthesis is chalcone synthase (CHS, EC 2.3.1.74). The genomic DNA of CHS was studied in six chamomile specimens from different genotypes to describe interspecimen, as well as interspecific, variability. One specimen of M. discoidea was included as an outgroup. The two exons of CHS of M. chamomilla (McCHS) and M. discoidea (MdCHS) were 188 bp and 1,011 bp long, separated by an intron of variable length between 192 and 199 bp in McCHS and 201 bp in MdCHS, respectively. The two exons with 5.3 and 6.2 mutations per 100 bp, respectively, were more conserved than the intron with 11.5 mutations per 100 bp. In total, 96 SNPs were detected in both species, of which 12 SNPs were only present in MdCHS and 80 SNPs only in McCHS. Overall, 70 haplotypes (multilocus genotypes, MLGs) were detected. The samples could be classified into two groups, a 'compact' group of a low number and diversity of haplotypes and a 'variable' group of a high number and diversity of haplotypes. Of the 74 SNPs in McCHS, only six SNPs were non-synonymous. However, the amino acid changes did not affect critical areas of the enzyme. The combination of the six SNPs resulted in nine translated amino acid MLGs. The CHS network located MdCHS, due to the crossing barrier, quite distant from chamomile. MdCHS docked to McCHS at a position from where McCHS divergently evolved into two directions.

High-Quality Assembly and Analysis of the Complete Mitogenomes of German Chamomile (Matricaria recutita) and Roman Chamomile (Chamaemelum nobile).

German chamomile (Matricaria chamomilla L.) and Roman chamomile (Chamaemelum nobile) are the two well-known chamomile species from the Asteraceae family. Owing to their essential oils and higher medicinal value, these have been cultivated widely across Europe, Northwest Asia, North America, and Africa. Regarding medicinal applications, German chamomile is the most commonly utilized variety and is frequently recognized as the "star among medicinal species". The insufficient availability of genomic resources may negatively impact the progression of chamomile industrialization. Chamomile's mitochondrial genome is lacking in extensive empirical research. In this study, we achieved the successful sequencing and assembly of the complete mitochondrial genome of M. chamomilla and C. nobile for the first time. An analysis was conducted on codon usage, sequence repeats within the mitochondrial genome of M. chamomilla and C. nobile. The phylogenetic analysis revealed a consistent positioning of M. chamomilla and C. nobile branches within both mitochondrial and plastid-sequence-based phylogenetic trees. Furthermore, the phylogenetic analysis also showed a close relationship between M. chamomilla and C. nobile within the clade comprising species from the Asteraceae family. The results of our analyses provide valuable resources for evolutionary research and molecular barcoding in chamomile.

Establishment and validation of a callus tissue transformation system for German chamomile (Matricaria chamomilla L.).

BACKGROUND: German chamomile (Matricaria chamomilla L.) is an important medicinal plant, and the essential oils in the flowers have various biological activities. Genetic transformation systems are important for plant quality improvement and molecular research. To the best of our knowledge, a genetic transformation system has not yet been reported for German chamomile. RESULTS: In this study, we developed Agrobacterium-mediated transformation protocols for German chamomile callus tissues. This involved optimizing key parameters, such as hygromycin and cefotaxime concentrations, bacterial density, and infection and co-culture durations. We also performed gas chromatography-mass spectrometry analysis to identify volatile compounds in non-transgenic and transgenic callus and hairy root tissues. Furthermore, to compare and verify the callus transformation system of German chamomile, we transferred McFPS to the hairy roots of German chamomile. The results showed that the optimal conditions for Agrobacterium-mediated callus tissue transformation were as follows: explant, petiole; cefotaxime concentration, 300 mg/L; hygromycin concentration, 10 mg/L; and bacterial solution concentration, OD600 = 0.6; callus transformation efficiency was the highest when the co-culture time was 3 days. CONCLUSIONS: Establishment of a high-efficiency callus transformation system will lay the foundation for gene function identification in German chamomile.

Investigation on pollination approaches, reproductive biology and essential oil variation during floral development in German chamomile (Matricaria chamomilla L.).

German chamomile is an important medicinal and aromatic herb known for its blue essential oil. It lacks studies on anthesis, breeding systems and floral development with their impact on the essential oil. Therefore, the study investigated floral development and divided it into six reproductive stages (RS-1 to RS-6). The first four stages (5-6 days long) were identified as the floral enlargement and differentiation, followed by the fifth stage (10 days long) of three anthesis flushes, i.e., anther dehiscence, ray and disc florets' style branches flush. Anther dehiscence started 1-2 days before style branches flushes showed protandry and overlapped later with style branches flushes. Pollen production started from RS-3 and showed maximum viability (89%) at anther dehiscence (RS-5.1). Pollen showed dispersal through the air up to 0.7 m distance. Seed setting in controlled pollination experiments showed that removing disc florets could be successfully used as the emasculation alternate in German chamomile. The maximum essential oil content (0.40%) at the full blossomed floral stage (RS-4 &-5) suggested the right time for capitula harvesting. The findings on reproductive biology and breeding systems would offer several tools and techniques to support future breeding programs for genetic improvement of German chamomile.

Unusual deletion of the maternal 11p15 allele in Beckwith-Wiedemann syndrome with an impact on both imprinting domains.

BACKGROUND: Whereas duplications in 11p15.5 covering both imprinting centers (ICs) and their subordinated genes account for up to 1% of Beckwith-Wiedemann and Silver-Russell syndrome patients (BWS, SRS), the deletions in 11p15.5 reported so far only affect one of the ICs. In these cases, not only the size and gene content had an impact on the phenotype, but also the sex of the contributing parent influences the clinical signs of the deletion carrier. RESULTS: We here report on the first case with a heterozygous deletion within the maternal allele affecting genes which are regulated by both ICs in 11p15.5 in a BWS patient, and describe the molecular and clinical consequences in case of its maternal or paternal inheritance. CONCLUSIONS: The identification of a unique deletion affecting both 11p15.5 imprinting domains in a BWS patient illustrates the complexity of the regulation mechanisms in these key imprinting regions.

Mitochondrial relationships between various chamomile accessions.

Matricaria chamomilla L. (GRIN; The Plant List 2013) is an important medicinal plant and one of the most frequently consumed tea plants. In order to assess mitochondrial genome variation of different cultivated chamomile accessions, 36 mitochondrial SNP markers were used in a HRM (high resolution melting) approach. In thirteen accessions of chamomile (n = 155), twenty mitochondrial haplotypes (genetic distances 0.028-0.693) were identified. Three of the accessions ('Camoflora', 'Mat19' and 'Manzana') were monomorphic. The highest genotypic variability was found for the Croatian accession 'PG029' with nine mitochondrial haplotypes (mitotypes) and the Argentinian 'Argenmilla' with seven mitotypes. However, most of the mitotypes detected in these accessions were infrequent in our sample set, thus disclosing an unusual high amount of substitutions within the mitochondrial genome of these accessions. The mitotypes with the highest frequency in the examined dataset were MT1 (n = 27), MT9 (n = 23) and MT17 (n = 20). All of the frequent mitochondrial lines are distributed not only over several accessions but also over several geographical origins. The origins often build a triplet with on average two to three concurrent lines. The most distantly related accessions were 'Mat19' and 'Camoflora' (0.539), while 'PNOS' and 'Margaritar' (0.007) showed the lowest genetic distance.

Cloning and functional analysis of three aphid alarm pheromone genes from German chamomile (Matricaria chamomilla L.).

German chamomile (Matricaria chamomilla L.) is one of the most ancient medicinal species in the world and terpenoids from their flowers have important medicinal value. We cloned three sesquiterpene synthase genes, McGDS1, McGDS2 and McGDS3, and performed sequence alignment and phylogenetic analysis. The encoded proteins possess three conserved structural features: an RRxxxxxxxxW motif, an RxR motif, and a DDxxD motif. McGDS1, McGDS2 and McGDS3 were confirmed to be (E)-farnesene synthase, germacrene D synthase, and germacrene A synthase, respectively. Subcellular localization revealed diffuse GFP reporter-gene signals in the cytoplasm and nucleus. qPCR indicated that McGDS1, McGDS2 and McGDS3, were more highly expressed in young flowers than in old flowers and the expression was highly correlated with amounts of the end-product essential oils ((E)-ß-farnesene, germacrene D and ß-elemene), with coefficients of 0.76, 0.83 and 0.68, respectively. We also established a transformation system for chamomile hairy roots. The overexpression of McGDS1, McGDS2 and McGDS3 resulted in γ-muurolene accumulation in hairy roots. The activity of three aphid alarm pheromones here forms the molecular basis for the study of the biosynthesis and regulation of volatile terpenes. Transformation of chamomile hairy roots provides a simple system in which to study terpene biosynthesis in chamomile.

Phytochemical and comparative transcriptome analyses reveal different regulatory mechanisms in the terpenoid biosynthesis pathways between Matricaria recutita L. and Chamaemelum nobile L.

BACKGROUND: Matricaria recutita (German chamomile) and Chamaemelum nobile (Roman chamomile) belong to the botanical family Asteraceae. These two herbs are not only morphologically distinguishable, but their secondary metabolites - especially the essential oils present in flowers are also different, especially the terpenoids. The aim of this project was to preliminarily identify regulatory mechanisms in the terpenoid biosynthetic pathways that differ between German and Roman chamomile by performing comparative transcriptomic and metabolomic analyses. RESULTS: We determined the content of essential oils in disk florets and ray florets in these two chamomile species, and found that the terpenoid content in flowers of German chamomile is greater than that of Roman chamomile. In addition, a comparative RNA-seq analysis of German and Roman chamomile showed that 54% of genes shared > 75% sequence identity between the two species. In particular, more highly expressed DEGs (differentially expressed genes) and TF (transcription factor) genes, different regulation of CYPs (cytochrome P450 enzymes), and rapid evolution of downstream genes in the terpenoid biosynthetic pathway of German chamomile could be the main reasons to explain the differences in the types and levels of terpenoid compounds in these two species. In addition, a phylogenetic tree constructed from single copy genes showed that German chamomile and Roman chamomile are closely related to Chrysanthemum nankingense. CONCLUSION: This work provides the first insights into terpenoid biosynthesis in two species of chamomile. The candidate unigenes related to terpenoid biosynthesis will be important in molecular breeding approaches to modulate the essential oil composition of Matricaria recutita and Chamaemelum nobile.

Analysis of terpenoid biosynthesis pathways in German chamomile (Matricaria recutita) and Roman chamomile (Chamaemelum nobile) based on co-expression networks.

German chamomile and Roman chamomile are the two most widely known chamomile species due to the medicinal properties of volatile compounds from their flowers. We determined the volatile compound content of different organs of these two chamomiles, and found that main volatile compounds in German chamomile were terpenoids and those in Roman chamomile were esters. Furthermore, 24 tissues from two chamomiles were sequenced and analyzed by gene co-expression network. The results showed higher terpene synthase expression levels and more modules correlated with sesquiterpenoids in German chamomile, which may explain its high sesquiterpenoid content. In both chamomiles, unigenes in volatile compound-correlated modules were significantly enriched in pathways related to plant-pathogen interactions and circadian rhythm, demonstrating that volatile compounds of chamomiles are influenced by these factors. There were ten times more unigenes related to plant-pathogen interactions in German chamomile than in Roman chamomile, which indicates German chamomile has higher resistance to pathogens.

The Role of Auxin in the Pattern Formation of the Asteraceae Flower Head (Capitulum).

Nature often creates complex structures by rearranging pre-existing units. One such example is the flower head (capitulum) in daisies, where a group of flowers (florets) and phyllaries (modified bracts) are arranged to superficially mimic a single flower. The capitulum is a key taxonomical innovation that defines the daisy family (Asteraceae), the largest flowering plant group. However, patterning mechanisms underlying its structure remain elusive. Here, we show that auxin, a plant hormone, provides a developmental patterning cue for the capitulum. During capitulum development, a temporal auxin gradient occurs, regulating the successive and centripetal formation of distinct florets and phyllaries. Disruption of the endogenous auxin gradient led to homeotic conversions of florets and phyllaries in the capitulum. Furthermore, auxin regulates floral meristem identity genes, such as Matricaria inodora RAY2 and M inodora LEAFY, which determine floret and phyllary identity. This study reveals the mechanism of capitulum patterning and highlights how common developmental tools, such as hormone gradients, have independently evolved in plants and animals.

A genome size and phylogenetic survey of Mediterranean Tripleurospermum and Matricaria (Anthemideae, Asteraceae).

The study of genome size variation can contribute valuable information on species relationships as well as correlate to several morphological or ecological features, among others. Here we provide an extensive report on genome sizes on genus Tripleurospermum and its closely related genus Matricaria, which are two typically Mediterranean genera particularly widespread and diverse in Turkey, the origin of most of the populations here studied. We analyse and discuss genome size variation in the first relatively complete molecular phylogenetic framework of Tripleurospermum (based on ITS and ETS ribosomal DNA-rDNA-regions). We find cases of intraspecific genome size variation, which could be taxonomically significant. Genome downsizing is also detected as the typical response to polyploidisation in Tripleurospermum taxa, being most conspicuous at the tetraploid level. Several positive correlations with genome size, including those with pollen and stomatal size or cypsela length, among others, are also found. Remarkably, taxa presenting rhizomes tend to present higher genome sizes, confirming a trend to accumulate nuclear DNA in such species, which could be explained by the nutrient reserves availability in their storage organs, allowing genome expansion, or by the lower rates of sexual reproduction in rhizomatous taxa.

The potential of three different PCR-related approaches for the authentication of mixtures of herbal substances and finished herbal medicinal products.

BACKGROUND: Herbal substances and preparations thereof play an important role in healthcare systems worldwide. Due to the variety of these products regarding origin, composition and processing procedures, appropriate methodologies for quality assessment need to be considered. A majority of herbal substances is administered as multicomponent mixtures, especially in the field of Traditional Chinese Medicine and ayurvedic medicine, but also in finished medicinal products. Quality assessment of complex mixtures of herbal substances with conventional methods is challenging. Thus, emphasis of the present work was directed on the development of complementary methods to elucidate the composition of mixtures of herbal substances and finished herbal medicinal products. HYPOTHESIS/PURPOSE: An indispensable prerequisite for the safe and effective use of herbal medicines is the unequivocal authentication of the medicinal plants used therein. In this context, we investigated the potential of three different PCR-related methods in the characterization and authentication of herbal substances. METHODS: A multiplex PCR assay and a quantitative PCR (qPCR) assay were established to analyze defined mixtures of the herbal substances Quercus cortex, Juglandis folium, Aristolochiae herba, Matricariae flos and Salviae miltiorrhizae radix et rhizoma and a finished herbal medicinal product. Furthermore, a standard cloning approach using universal primers targeting the ITS region was established in order to allow the investigation of herbal mixtures with unknown content. RESULTS: The cloning approach had some limitations regarding the detection/recovery of the components in defined mixtures of herbal substances, but the complementary use of two sets of universal primer pairs increased the detection of components out of the mixture. While the multiplex PCR did not retrace all components in the defined mixtures of herbal substances, the established qPCR resulted in simultaneous and specific detection of the five target sequences in all defined mixtures. CONCLUSION: These data indicate that for authentication purposes, complementary PCR-related methods are highly recommendable for the analysis of herbal mixtures in parallel.

In vitro characterization of a (E)-ß-farnesene synthase from Matricaria recutita L. and its up-regulation by methyl jasmonate.

(E)-ß-farnesene is a sesquiterpene semiochemical that is used extensively by both plants and animals for communication. This acyclic olefin is found in the essential oil of chamomile (Matricaria recutita) and was demonstrated that it could attract natural enemies to reduce cabbage aphids in the Chinese cabbage fields. However, little is known regarding the sequence and function of (E)-ß-farnesene synthase in M. recutita. In this study, we reported a new full-length cDNA encoding (E)-ß-farnesene synthase from M. recutita (Mr-ßFS). The cDNA of Mr-ßFS consisted of 2010bp including 1725bp of coding sequence encoding a protein of 574 amino acids with a molecular weight of 67kDa. The deduced amino acid sequence exhibits a considerably higher homology to ßFS from Artemisia annua (about 92% identity) than to ßFSs from other plants (about 20-40% identity). The recombinant enzyme, produced in Escherichia coli, catalyzed the formation of a single product, (E)-ß-farnesene, from farnesyl diphosphate. Real-time quantitative PCR (qRT-PCR) analysis showed that Mr-ßFS expression was highest in leaves and lowest in disk florets. The treatment of M. recutita with methyl jasmonate (MeJA) significantly enhanced the transcriptional level of ßFS gene and the content of (E)-ß-farnesene in M. recutita. The transcriptional level of ßFS gene was approximately 11.5-fold higher than the control sample and the (E)-ß-farnesene emission level ranged from approximately from 0.082 to 0.695µg/g after 24h induction. Our results laid a solid foundation for later improving crop aphid resistance by transgenic technology and provided an important basic data for the regulation of valuable products from M. recutita.

Cloning and characterization of a farnesyl pyrophosphate synthase from Matricaria recutita L. and its upregulation by methyl jasmonate.

Matricaria recutita (L.), commonly known as chamomile, is one of the most valuable medicinal plants because it synthesizes a large number of pharmacologically active secondary metabolites known as α-bisabolol and chamazulene. Although the plant has been well characterized in terms of chemical constituents of essential oil as well as pharmacological properties, little is known about the genes responsible for biosynthesis of these compounds. In this study, we report a new full-length cDNA encoding farnesyl diphosphate synthase (FPS), a key enzyme in the pathway of biosynthesis of isoprenoids, from M. recutita. The cDNA of MrFPS comprises 1032 bp and encodes 343 amino acid residues with a calculated molecular mass of 39.4 kDa. The amino acid sequence homology and phylogenetic analysis indicated that MrFPS belongs to the plant FPS super-family and is closely related to FPS from the Asteraceae family. Expression of the MrFPS gene in Escherichia coli yielded FPS activity. Using real-time quantitative PCR, the expression pattern of the MrFPS gene was analyzed in different tissues of M. recutita as well as in response to methyl jasmonate. The expression analysis demonstrated that MrFPS expression varies in different tissues (with maximal expression in flowers and stems) and was significantly elevated in response to methyl jasmonate. This study will certainly enhance our understanding of the role of MrFPS in the biosynthesis and regulation of valuable secondary metabolites in M. recutita at a molecular level.

Molecular cloning and characterization of the full-length Hsp90 gene from Matricaria recutita.

Heat shock protein 90 (Hsp90) is one of the most abundant and conserved chaperone proteins and plays important roles in plant growth and responses to environmental stimuli. However, little is known regarding the sequence and function of Hsp90s in Matricaria recutita. In the present study, we cloned the full-length cDNA sequence of the hsp90 gene from this species. Using rapid amplification of cDNA ends technologies with 2 degenerate primers that were designed based on the hsp90 gene sequence from other members of Asteraceae, we isolated and characterized an Hsp90 homolog gene from M. recutita (Mr-Hsp90). The full-length Mr-hsp90 cDNA sequence, containing 2097 base pairs, encodes a protein of 698 amino acids. Based on amino acid sequence identity, Mr-Hsp90 showed high similarity to other cloned Hsp90 proteins. The Mr-Hsp90 protein was closely clustered with the Lactuca sativa in a phylogenetic tree. These results indicate that the cloned sequence of Mr-Hsp90 is a member of the Hsp90 family, which is reported for the first time in M. recutita. Next, we conducted a salt stress experiment to determine the protein's function under salt stress conditions. Survival of chamomile seedlings subjected to heat-shock pretreatment was significantly increased compared with groups that had not undergone heat-shock pretreatment in a salt stress environment. This indicates that Mr-Hsp90 plays an important role in the salt resistance of chamomile seedlings.

Enantioselective microbial synthesis of the indigenous natural product (-)-α-bisabolol by a sesquiterpene synthase from chamomile (Matricaria recutita).

(-)-α-Bisabolol, a sesquiterpene alcohol, is a major ingredient in the essential oil of chamomile (Matricaria recutita) and is used in many health products. The current supply of (-)-α-bisabolol is mainly dependent on the Brazilian candeia tree (Eremanthus erythropappus) by distillation or by chemical synthesis. However, the distillation method using the candeia tree is not sustainable, and chemical synthesis suffers from impurities arising from undesirable α-bisabolol isomers. Therefore enzymatic synthesis of (-)-α-bisabolol is a viable alternative. In the present study, a cDNA encoding (-)-α-bisabolol synthase (MrBBS) was identified from chamomile and used for enantioselective (-)-α-bisabolol synthesis in yeast. Chamomile MrBBS was identified by Illumina and 454 sequencing, followed by activity screening in yeast. When MrBBS was expressed in yeast, 8 mg of α-bisabolol was synthesized de novo per litre of culture. The structure of purified α-bisabolol was elucidated as (S,S)-α-bisabolol [or (-)-α-bisabolol]. Although MrBBS possesses a putative chloroplast-targeting peptide, it was localized in the cytosol, and a deletion of its N-terminal 23 amino acids significantly reduced its stability and activity. Recombinant MrBBS showed kinetic properties comparable with those of other sesquiterpene synthases. These data provide compelling evidence that chamomile MrBBS synthesizes enantiopure (-)-α-bisabolol as a single sesquiterpene product, opening a biotechnological opportunity to produce (-)-α-bisabolol.

Short-term UV-B dose stimulates production of protective metabolites in Matricaria chamomilla leaves.

Physiological response of two cultivars of Matricaria chamomilla plants on UV irradiation was studied. The impact of used short-time UV dose was evaluated in three time points; 2, 24 and 48 h after irradiation. Used UV irradiation immediately resulted in changes in plant oxidative status monitored as increased concentration of H2 O2 . Decrease in chlorophyll a and b indicated the impact on photosynthetic apparatus. For phenolic secondary metabolites, an increase in total soluble phenols and AlCl3 -reactive flavonols was observed. The activity of main phenolic enzyme, phenylalanine ammonia-lyase, increased with time after irradiation. Significant changes, mainly decreasing trends, in the content of free coumarins and their glycosidic precursors were observed. Enhanced accumulation in chlorogenic and 1,5-dicaffeoylquinic acid and in (Z)-isoform of dicycloethers was detected. From these results, the redirecting precursors of coumarin biosynthesis to biosynthesis of substances with higher antioxidative potential can be assumed. Different reactions in diploid and tetraploid plants were recorded, too.

Estimating economic thresholds for site-specific weed control using manual weed counts and sensor technology: an example based on three winter wheat trials.

BACKGROUND: Precision experimental design uses the natural heterogeneity of agricultural fields and combines sensor technology with linear mixed models to estimate the effect of weeds, soil properties and herbicide on yield. These estimates can be used to derive economic thresholds. Three field trials are presented using the precision experimental design in winter wheat. Weed densities were determined by manual sampling and bi-spectral cameras, yield and soil properties were mapped. RESULTS: Galium aparine, other broad-leaved weeds and Alopecurus myosuroides reduced yield by 17.5, 1.2 and 12.4 kg ha(-1) plant(-1) m(2) in one trial. The determined thresholds for site-specific weed control with independently applied herbicides were 4, 48 and 12 plants m(-2), respectively. Spring drought reduced yield effects of weeds considerably in one trial, since water became yield limiting. A negative herbicide effect on the crop was negligible, except in one trial, in which the herbicide mixture tended to reduce yield by 0.6 t ha(-1). Bi-spectral cameras for weed counting were of limited use and still need improvement. Nevertheless, large weed patches were correctly identified. CONCLUSION: The current paper presents a new approach to conducting field trials and deriving decision rules for weed control in farmers' fields.

Copper uptake is differentially modulated by phenylalanine ammonia-lyase inhibition in diploid and tetraploid chamomile.

The effect of phenylalanine ammonia-lyase (PAL) inhibition by 2-aminoindane-2-phosphonic acid (AIP) in copper-exposed diploid and tetraploid chamomile (Matricaria chamomilla ) roots has been studied in a short-term experiment (24 h). Cu evoked stronger induction of PAL activity and accumulation of soluble phenols, flavonols (quercetin and kaempferol), and lignin in diploid plants, whereas AlCl3-reactive flavonoids and phenolic acids did not differ with respect to ploidy. Amounts of hydrogen peroxide and superoxide also preferentially increased in diploid. Surprisingly, PAL activity was restored in both +AIP cultivars, being inversely correlated with the accumulation of free phenylalanine. Notwithstanding this, total soluble phenols and flavonols were more depleted in Cu+AIP diploid roots. Soluble proteins decreased in response to Cu, and AIP had no effect. Among free amino acids, proline increased more visibly in Cu+AIP diploid, suggesting that this could be a protective mechanism in conditions with depleted content of phenols. Decrease in potassium content was ploidy-independent, calcium increased in all Cu variants, and Fe increased in Cu-exposed tetraploid. Shoot Cu content did not differ in Cu-exposed cultivars, but diploid roots contained more Cu. AIP decreased root Cu but increased shoot Cu amounts in diploid, whereas tetraploid plants did not exhibit similar responses. These data indicate that inhibition of root phenolic metabolism by AIP was effective enough, allowing Cu to accumulate in diploid shoots. The present findings are discussed in the context of available data about AIP effects and with respect to the role of phenols in metal uptake.

Role of ploidy in cadmium and nickel uptake by Matricaria chamomilla plants.

Cadmium and nickel uptake by diploid and tetraploid chamomile (Matricaria chamomilla L.) cultivars (Novbona and Lutea, respectively) exposed to 60 microM solutions of individual metals over 7 days was studied. Diploid plants accumulated higher amount of Cd in both shoots and roots compared to tetraploid plants while Ni accumulation was ploidy-independent. Cd presence caused higher accumulation of total soluble phenols and flavonoids and higher phenylalanine ammonia-lyase and guaiacol-peroxidase activities in diploid cultivar in comparison with tetraploid but phenolic acids did not show direct correlation with metal accumulation and even decreased in the leaves of Ni-exposed plants. Lignin content was preferentially elevated in the roots of diploid cultivar. Among 17 free amino acids, their sum increased mainly in the leaves of Cd-exposed plants (owing to increase in serine, alanine and proline). Potassium decrease in both cultivars in response to Cd was ploidy-independent and Ca, Mg and Fe accumulation were almost unaffected. It is concluded that Cd accumulation in chamomile may be mediated by the accumulation of phenols but they have no active role in shoot Ni accumulation. Present findings in the context of our previous studies and limited available literature about ploidy effect on metal accumulation are discussed.